code: def is_in_expr(expr, find):
      """Returns True if `find` is a subtree of `expr`."""
      return expr == find or (
          isinstance(expr, ExprNode) and expr.is_in(find)
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from collections import namedtuple
  import random
  import six
  from six.moves import range
  import sympy
label_desc: Use image node_id 1 for calling a global function with example usage: is_in_expr(expr, find) and returns: unknown